Practically, the only software for font editing on Mac that is constantly being developed, updated, supported etc. is FontLab (currently at version 4.6): http://www.fontlab.com
Apart from the flagship application (FontLab), the company Fontlab Ltd. offers other tools for font-related work: ScanFont (a FontLab plugin for turning bitmaps into outline fonts), TransType (a font formats converter), BitFonter (a bitmap font editor), TypeTool (a lightweight version of FontLab), and others. Some of the applications are available for both Mac and Windows, while others are only available on one platform.
Visit http://www.fontlab.com for more details.
Regards,
Adam

I too would love to find a copy of FontChameleon!
I actually have FC 1.5 (the starter version) for the Mac. I am VERY interested in purchasing either the pro version (with all the type descriptors) for EITHER Mac or PC, OR the additional type pack(s) for the 1.5 Mac version. I am VERY motivated to find one or both! If you have ANY information relating to locating a copy of FontChameleon OR the additional type library, please contact me.
Thanks so much for your attention, and any help you may be able to offer!
Ken Ryan
KR Studio
Braintree, MA

an excellent choice is pfaedit -

I would love to find FontChameleon

Ken,
if you ever wish to sell FontChameleon, let me know! I have V1 and it is great but, no true italics.
How many fonts did 1.5 come with? I know 1.5 pro came with 220 or so.

Rodi

The Truth shall set you free

pfaedit is now known as FontForge. It is free, open source software that runs quite nicely on Mac OS X (10.3-ish and up) with X11, once you get used to its non-Mac-ness. It's updated and improved continuously, with full rebuilds on a nearly monthly basis.